Create feature flag allow-empty-values (#7)

This PR address #8, introducing our first feature flag to allow for
parsing lines that have a key but no value.

We also enable running the tests with all features enabled as well as
the default.

Signed-off-by: Kyle Rader <[email protected]>
Co-authored-by: Kyle Rader <[email protected]>

.github/workflows/ci.yml

@@ -30,10 +30,15 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: build
-      - name: Unit Tests
+      - name: Unit Tests (default features)
         uses: actions-rs/cargo@v1
         with:
           command: test
+      - name: "Unit Tests (all features)"
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: "--all-features"
   quality:
     name: Code Quality
     runs-on: ubuntu-latest

Cargo.toml

@@ -13,8 +13,11 @@ edition = "2021"
 
 authors = ["TheDaemoness"]
 include = ["/src", "/README.md", "/DOC.md"]
-rust-version = "1.56" # 2021 edition
+rust-version = "1.56"                       # 2021 edition
 version = "1.0.2"
 
 [workspace]
 members = ["tools"]
+
+[features]
+allow-empty-values = []

src/linereader.rs

@@ -48,10 +48,19 @@ pub fn parse_line(line: &str) -> LineReadResult<'_> {
     } else if let Some((key_raw, val_raw)) = l.split_once('=') {
         let key = key_raw.trim_end();
         let val = val_raw.trim_start();
-        if key.is_empty() || val.is_empty() {
-            Err(ParseError::InvalidLine)
-        } else {
-            Ok(Line::Pair(key.trim_end(), val.trim_start()))
+        match (key.is_empty(), val.is_empty()) {
+            (true, _) => Err(ParseError::InvalidLine),
+            (false, true) => {
+                #[cfg(feature = "allow-empty-values")]
+                {
+                    Ok(Line::Pair(key.trim_end(), val))
+                }
+                #[cfg(not(feature = "allow-empty-values"))]
+                {
+                    Err(ParseError::InvalidLine)
+                }
+            }
+            (false, false) => Ok(Line::Pair(key.trim_end(), val.trim_start())),
         }
     } else {
         Err(ParseError::InvalidLine)

src/tests/linereader.rs

@@ -19,6 +19,10 @@ fn valid_props() {
         ("  foo =  bar = baz  ", Pair("foo", "bar = baz")),
         ("foo = bar #baz", Pair("foo", "bar #baz")),
         ("foo = [bar]", Pair("foo", "[bar]")),
+        #[cfg(feature = "allow-empty-values")]
+        ("foo =", Pair("foo", "")),
+        #[cfg(feature = "allow-empty-values")]
+        ("foo = ", Pair("foo", "")),
     ])
 }
 
@@ -64,8 +68,9 @@ fn invalid() {
         "][",
         "nonproperty",
         "=",
-        "noval =  ",
         "  = nokey",
+        #[cfg(not(feature = "allow-empty-values"))]
+        "noval = ",
     ];
     for line in lines {
         assert!(matches!(